arch/arm/mm/copypage-xscale.c

   1 /*
   2  *  linux/arch/arm/lib/copypage-xscale.S
   3  *
   4  *  Copyright (C) 1995-2005 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * This handles the mini data cache, as found on SA11x0 and XScale
  11  * processors.  When we copy a user page page, we map it in such a way
  12  * that accesses to this page will not touch the main data cache, but
  13  * will be cached in the mini data cache.  This prevents us thrashing
  14  * the main data cache on page faults.
  15  */
  16 #include <linux/init.h>
  17 #include <linux/mm.h>
  18 #include <linux/highmem.h>
  19
  20 #include <asm/pgtable.h>
  21 #include <asm/tlbflush.h>
  22 #include <asm/cacheflush.h>
  23
  24 #include "mm.h"
  25
  26 #define minicache_pgprot __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | \
  27                                   L_PTE_MT_MINICACHE)
  28
  29 static DEFINE_RAW_SPINLOCK(minicache_lock);
  30
  31 /*
  32  * XScale mini-dcache optimised copy_user_highpage
  33  *
  34  * We flush the destination cache lines just before we write the data into the
  35  * corresponding address.  Since the Dcache is read-allocate, this removes the
  36  * Dcache aliasing issue.  The writes will be forwarded to the write buffer,
  37  * and merged as appropriate.
  38  */
  39 static void __naked
  40 mc_copy_user_page(void *from, void *to)
  41 {
  42         /*
  43          * Strangely enough, best performance is achieved
  44          * when prefetching destination as well.  (NP)
  45          */
  46         asm volatile(
  47         "stmfd  sp!, {r4, r5, lr}               \n\
  48         mov     lr, %2                          \n\
  49         pld     [r0, #0]                        \n\
  50         pld     [r0, #32]                       \n\
  51         pld     [r1, #0]                        \n\
  52         pld     [r1, #32]                       \n\
  53 1:      pld     [r0, #64]                       \n\
  54         pld     [r0, #96]                       \n\
  55         pld     [r1, #64]                       \n\
  56         pld     [r1, #96]                       \n\
  57 2:      ldrd    r2, [r0], #8                    \n\
  58         ldrd    r4, [r0], #8                    \n\
  59         mov     ip, r1                          \n\
  60         strd    r2, [r1], #8                    \n\
  61         ldrd    r2, [r0], #8                    \n\
  62         strd    r4, [r1], #8                    \n\
  63         ldrd    r4, [r0], #8                    \n\
  64         strd    r2, [r1], #8                    \n\
  65         strd    r4, [r1], #8                    \n\
  66         mcr     p15, 0, ip, c7, c10, 1          @ clean D line\n\
  67         ldrd    r2, [r0], #8                    \n\
  68         mcr     p15, 0, ip, c7, c6, 1           @ invalidate D line\n\
  69         ldrd    r4, [r0], #8                    \n\
  70         mov     ip, r1                          \n\
  71         strd    r2, [r1], #8                    \n\
  72         ldrd    r2, [r0], #8                    \n\
  73         strd    r4, [r1], #8                    \n\
  74         ldrd    r4, [r0], #8                    \n\
  75         strd    r2, [r1], #8                    \n\
  76         strd    r4, [r1], #8                    \n\
  77         mcr     p15, 0, ip, c7, c10, 1          @ clean D line\n\
  78         subs    lr, lr, #1                      \n\
  79         mcr     p15, 0, ip, c7, c6, 1           @ invalidate D line\n\
  80         bgt     1b                              \n\
  81         beq     2b                              \n\
  82         ldmfd   sp!, {r4, r5, pc}               "
  83         :
  84         : "r" (from), "r" (to), "I" (PAGE_SIZE / 64 - 1));
  85 }
  86
  87 void xscale_mc_copy_user_highpage(struct page *to, struct page *from,
  88         unsigned long vaddr, struct vm_area_struct *vma)
  89 {
  90         void *kto = kmap_atomic(to);
  91
  92         if (!test_and_set_bit(PG_dcache_clean, &from->flags))
  93                 __flush_dcache_page(page_mapping_file(from), from);
  94
  95         raw_spin_lock(&minicache_lock);
  96
  97         set_top_pte(COPYPAGE_MINICACHE, mk_pte(from, minicache_pgprot));
  98
  99         mc_copy_user_page((void *)COPYPAGE_MINICACHE, kto);
 100
 101         raw_spin_unlock(&minicache_lock);
 102
 103         kunmap_atomic(kto);
 104 }
 105
 106 /*
 107  * XScale optimised clear_user_page
 108  */
 109 void
 110 xscale_mc_clear_user_highpage(struct page *page, unsigned long vaddr)
 111 {
 112         void *ptr, *kaddr = kmap_atomic(page);
 113         asm volatile(
 114         "mov    r1, %2                          \n\
 115         mov     r2, #0                          \n\
 116         mov     r3, #0                          \n\
 117 1:      mov     ip, %0                          \n\
 118         strd    r2, [%0], #8                    \n\
 119         strd    r2, [%0], #8                    \n\
 120         strd    r2, [%0], #8                    \n\
 121         strd    r2, [%0], #8                    \n\
 122         mcr     p15, 0, ip, c7, c10, 1          @ clean D line\n\
 123         subs    r1, r1, #1                      \n\
 124         mcr     p15, 0, ip, c7, c6, 1           @ invalidate D line\n\
 125         bne     1b"
 126         : "=r" (ptr)
 127         : "0" (kaddr), "I" (PAGE_SIZE / 32)
 128         : "r1", "r2", "r3", "ip");
 129         kunmap_atomic(kaddr);
 130 }
 131
 132 struct cpu_user_fns xscale_mc_user_fns __initdata = {
 133         .cpu_clear_user_highpage = xscale_mc_clear_user_highpage,
 134         .cpu_copy_user_highpage = xscale_mc_copy_user_highpage,
 135 };